A hearing aid may be attached behind the ear through an adhesive interconnection unit as described in for example US2015063616. The interconnection unit is adhesively attached to the skin behind the ear and the hearing aid can then be connected to the interconnection unit since there is a coupling between the hearing aid and the interconnection unit. The coupling allows the hearing aid to be snapped on and off from the interconnection unit without removing the interconnection unit from the skin. The interconnection unit can be changed at intervals suitable for the skin, for example once a week.
When adhering an interconnection unit to the skin behind the ear it is very important to find the right position before pressing the interconnection unit towards the skin to adhere it since it is both a stress to the skin to remove it from the skin and also the adhesive properties of most adhesives are reduced after removing it from the skin so that when trying to attach the same adhesive surface again would this would result in a poorer adhesion to the skin.
The interconnection unit should be adhered to hair free skin behind the ear since adhesion to a hairy area is usually poor. It is therefore important that the interconnection unit is not placed too far to the rear behind the ear since it would then be at least partly adhered to the hair baring area and the adhesion would be very poor. It is however also important that the interconnection unit does not touch the outer ear since this may be uncomfortable. The interconnection unit is usually quite flat so it will go under the main part of the outer ear so if it would be placed too close to the outer ear it would touch the outer ear in the outer ear fold behind the outer ear.
The position of the interconnection unit on the skin surface behind the ear decides also the position of the hearing aid in relation to the outer ear when the hearing aid is connected to the interconnection unit. The hearing aid must also not touch the outer ear since this may be uncomfortable and since this may also cause acoustic feedback. It is therefore very important that the interconnection unit is adhered to the skin behind the ear in a correct position so that the hearing aid does not touch the outer ear when the hearing aid is connected to the interconnection unit. Depending on the individual size and shape of the outer ear, it may be either the interconnection unit or the hearing aid that would be the most likely part of the hearing aid system to touch the outer ear.
The hairless skin area behind the ear is quite limited in size so the precision in the positioning of the interconnection unit has to be very accurate. At the same time it is difficult for the user to see behind the ear when adhering the interconnection unit even if a mirror is used.
The optimal position of the hearing aid and interconnection unit is close to the ear, but without any of the interconnection unit or the hearing aid touching the outer ear. It is a challenge to try to position the interconnection with the current hearing aid systems. There is a need for a more effective and user friendly adhesive hearing aid system that is reliable and does not have the drawbacks discussed above.